/Engine/Source/Editor/UnrealEd/Public/Utils.h
Utility for calculating drag direction when you click on this widget.
virtual void CalcVectors ( [FSceneView](API\Runtime\Engine\FSceneView) * SceneView, const [FViewportClick](API\Editor\UnrealEd\FViewportClick) & Click, FVector & LocalManDir, FVector & WorldManDir, float & DragDirX, float & DragDirY )